Resin Transfer Moulding Technique Research Articles

Analyzing the Tensile Strength of Carbon Fiber-Reinforced Epoxy Composites Using LabVIEW Virtual Instrument

Carbon fiber-reinforced polymer composites are widely used materials in the aircraft industry, automotive sector, marine applications, civil engineering, and daily consumer goods, due to their superior mechanical properties at a relatively low density compared to metallic materials. The studied composites are composed of an epoxy resin matrix in which three layers of carbon fiber fabric are embedded, oriented at 0 and 90 degrees. Carbon fiber-reinforced polymer composites were manufactured using the Vacuum Assisted Resin Transfer Molding technique. The tensile failure mechanism in carbon fiber-reinforced polymer composites is an extremely complex phenomenon influenced by numerous factors. This study aims to evaluate the mechanical behavior of carbon fiber-reinforced composites through tensile testing and to compare experimentally obtained results with those calculated using the mixture rule. Additionally, the behavior of the materials under tensile stress was analyzed using the digital image correlation method. Estimating mechanical properties based on the mixture rule is a common practice in the design phase of polymer composites. This study s novelty and originality lie in its anticipation of the tensile strength and modulus of elasticity of the studied composites. This anticipation was achieved using a virtual instrument developed in the LabVIEW graphical programming environment. The experimentally obtained results for the tensile characteristics of the studied materials are suitable for this type of composite. These results were compared with estimates derived from the mixture rule, and the absolute error was determined.

Experimental investigation of conductive heat transfer and fire protection in a polymer-based plate heat exchanger

Polymer-based heat exchangers offer several attractive features for thermal management applications such as low-cost, lightweight, antifouling, and anti-corrosion characteristics. However, their thermal performance is compromised primarily by the low thermal conductivity and high-flammability. This work consists of developing new polymer-based plate heat exchangers, which are made from epoxy resin reinforced by banana fibres and manufactured using the vacuum bag resin transfer moulding technique. The aim of this research is to improve both the heat transfer efficiency and thermal protection. The proposed approach involves incorporating silicon carbide powder as charge into samples to increase their thermal conductivity, and applying an intumescent fire-retardant coating to improve their capacity to withstand heat and flames. To determine the efficacy of this approach, a cone calorimetry test was performed to examine the thermal distribution within the plate heat exchanger samples and to assess fire reaction parameters during a fire scenario. The results revealed a notable increase in thermal conductivity, due to the addition of silicon carbide powder. Furthermore, the intumescent fire-retardant coating substantially improved the samples’ thermal resistance. This result has been verified by thermogravimetric analysis conducted during this work. These findings suggest that using banana fibres-reinforced epoxy resin, combined with silicon carbide powder and intumescent fire-retardant coating, has the potential to enhance the overall thermal performances of plate heat exchangers. The addition of silicon carbide powder increases the thermal conductivity by 36%. This demonstrates the feasibility of utilizing sustainable and biodegradable materials to manufacture heat exchangers that are more efficient and eco-friendly.

Void formation and suppression in CFRP laminate using newly designed ultrasonic vibration assisted RTM technique

This study introduces an ultrasonic vibration assisted resin transfer molding (RTM) technique as an innovative approach to address the inherent challenges associated with traditional methods for producing CFRP laminates. It investigates the mechanism of void formation in CFRP composites under ultrasonic vibration using 3D X-ray microscopy. Numerical calculations and simulation analyses are also employed to validate the impact of ultrasonic vibration on mechanical properties of CFRP. The findings indicate that ultrasonic vibration results in CFRP laminates with more uniform thickness, leading to a substantial increase in fiber volume fraction up to ∼16 %. Concurrently, there are significant improvements in flexural strength (∼20 %) and fracture energy (∼90 %). Ultrasonic vibration also effectively reduces CFRP porosity by at least 25 %, resulting in a more consistent distribution of voids, primarily consisting of small circular voids. This porosity reduction is attributed to the cavitation effect and enhancing wettability, consequently improving the mechanical properties of CFRP. Moreover, simulations and numerical calculations demonstrate the significant occurrence of cavitation effect within the resin under specific process conditions. The intensity of cavitation is influenced by factors such as the initial bubble radius, acoustic pressure amplitude, and static pressure of the resin. The ultrasonic-assisted RTM process is proved as a promising method for producing CFRP laminates with superior properties.

Failure prediction in a non-crimp basalt fibre reinforced epoxy composite

Failure analysis in non-crimp fabric (NCF) based fibre reinforced composite materials is challenging due to the complexity associated with multiaxial fabric architectures and the interaction of different failure modes. In this study an in-situ 3-point bend test under scanning electron microscopy (SEM) has been performed to analyse the failure behaviour of a NCF basalt epoxy composite manufactured by vacuum assisted resin transfer moulding (VaRTM) technique. The failure mechanisms observed during the in-situ 3-point bend test are compared to those from standard (ex-situ) flexure and interlaminar shear strength (ILSS) tests on the same material. Finite element analysis of each test configuration is also conducted to analyse the in-ply stress distributions and to predict the damage initiating stresses. The study reveals that fibre/matrix debonding leading to matrix cracking in the 90° sub-ply is the damage initiating failure mode, with final failure occurring due to fibre buckling in neighbouring 0° sub-plies. The finite element analysis reveals that matrix cracking in the 90° sub-ply is controlled by shear stresses ranging between 35 and 45 MPa.

Development of Interior and Exterior Automotive Plastics Parts Using Kenaf Fiber Reinforced Polymer Composite

The integration of sustainable components in automotive parts is in growing demand. This study involves the entire process, from the extraction of kenaf cellulosic fibers to the fabrication of automotive parts by applying injection molding (sample only) and Resin Transfer Molding (RTM) techniques. Fibers were pretreated, followed by moisture content analysis before composite fabrication. The composite was fabricated by integrating the fibers with polypropylene, maleic anhydride polypropylene (MAPP), unsaturated polyester, and epoxy resin. Mechanical tests were done following ASTM D5083, ASTM D256, and ASTM D5229 standards. The RTM technique was applied for the fabrication of parts with reinforced kenaf long bast fibers. RTM indicated a higher tensile strength of 55 MPa at an optimal fiber content of 40%. Fiber content from 10% to 40% was found to be compatible with or better than the control sample in mechanical tests. Scanning Electron Microscope (SEM) images showed both fiber-epoxy-PE bonding along with normal irregularities in the matrix. The finite element simulations for the theoretical analysis of the mechanical performance characteristics showed higher stiffness and strength in the direction parallel to the fiber orientation. This study justifies the competitiveness of sustainable textile fibers as a reinforcement for plastics to use in composite materials for automotive industries.

Effect of fire-retardant coating on bamboo and banana-based biocomposites: A comparative study thermogravimetric analysis and cone calorimeter tests

In this work, a thermal behaviour comparison of a new bamboo-based and banana-based Green Bio-Composites (GBC) is conducted using thermogravimetric analysis (TGA) and cone-calorimeter experiments. An Intumescent Fire-Retardant (IFR) coating (a mixture of Exolit IFR36 and boric acid) has been applied on the investigated GBC materials in order to explore the flammability resistance of such GBCs. Vacuum Bag Resin Transfer Moulding (VBRTM) technique has been used to manufacture the samples. TGA test have been conducted under oxidative atmosphere with three different heating rates while cone calorimeter tests have been performed with a horizontally exposure on the top surface of the sample. The outcomes of TGA revealed that Bamboo-based (BM-GBC) and Banana-based (Bn-GBC) materials exhibited similar thermal degradation patterns. However, BM-GBC outperformed Bn-based in the cone calorimetry analysis, this is proven by the fire reaction parameters as well as the higher char residue. In addition, IFR coating improved the flame retardancy of both GBCs, reduced the Peak Heat Release Rate (PHRR) by approximately 40–50% and smoke production (SEA) by 26%. SEM and EDS analysis of char residue were performed to deeply investigate the effectiveness of the IFR as a protecting layer.

The flexural properties of oil palm trunk (OPT) impregnated with epoxy (OPTE) composite manufactured by vacuum-assisted resin transfer moulding (VARTM) technique

Nowadays, the utilization of oil palm trunk (OPT) biomass has gained more interest in composite applications. This research presents the flexural properties of unimpregnated OPT and OPT impregnated with epoxy (OPTE) composites. The OPTE composites were fabricated using the vacuum-assisted resin transfer moulding (VARTM) technique. The unimpregnated OPT and OPTE composite specimens were selected from three different zones of longitudinal zone OPT namely Zone I (outer), Zone II (middle) and Zone III (inner), respectively. The flexural test was conducted according to ASTM D790. The results showed promising increases in flexural strength and flexural modulus of the OPTE composite in Zones I, II, and III compared to unimpregnated specimens, with increases of 254.09 % (49.79 MPa) and 158.78 % (4.14 GPa) in Zone I, 297.43 % (37.28 MPa) and 309.51 % (3.58 GPa) in Zone II, and 242.67 % (29.34 MPa) and 305.84 % (2.94 GPa) in Zone III, respectively. There was positive trend linear regression significantly observed in the relationship between flexural strength and modulus of elasticity (MOE) of OPTE composites and unimpregnated OPT of all three zones, respectively. The fractured flexural specimens of three different zones were analysed by using scanning electron microscopy (SEM). The improvement of OPTE composites is a possible as an alternative to replace the existence of commercial wood.

Experimental investigation on mechanical and thermal characteristics of waste sheep wool fiber-filled epoxy composites

With the escalating trends of environmental contamination, the necessity of exploring environment friendly composites has increased. Foreseeing a sustainable future, this study investigates mechanical and thermal characteristics of woven (W), and non– woven waste sheep wool fiber (N, C, F) reinforced epoxy composites. The composites are fabricated using the in-house Vacuum Assisted Resin Transfer Molding (VARTM) technique in a controlled environment. Using animal fiber-filled epoxy composites were created. The density, void content, hardness, and tensile strength of differentially ordered waste sheep wool fiber have been examined. Also, thermal characteristics such as effective thermal conductivity (Keff) and glass transition temperature (Tg) of the said composites have been evaluated. The results of the experimental investigation reveal that non-woven needle punched (N) animal fiber polymer composites exhibit good interfacial adhesion between fiber and matrix with lower void content and higher tensile strength. Also, waste animal fiber-woven (W) and felt (F) polymer composites exhibit better hardness and low thermal conductivity. Thus, it can be said that the fabricated waste sheep wool fiber-filled epoxy composites exhibit better mechanical and thermal characteristics for insulating building components.

Bearing performance improvement of single-lap, single-bolt basalt composite joints by locally strengthening the joint location using carbon fibre

The effect of local thickening with similar and different reinforcement materials for single-lap, single-bolt basalt composite joints was investigated. A vacuum-assisted resin transfer moulding technique was used to fabricate three types of test configurations, namely the reference basalt joint, the localised thickened joint using basalt fibre, and the localised thickened joint using the carbon fibre, i.e., localised carbon fibre hybridisation in sandwich-like and non-sandwich like manner. These configurations were tested under tensile loading and then examined using the Scanning Electron Microscopy (SEM). Laminating and thickening with a few layers of the same material (the basalt fibre) resulted in 56.6% and 104.6% improvement in load-bearing capacity and energy absorption, respectively. When these extra layers of basalt fibre for local thickening were replaced with the carbon fibre, an improvement of 80.2% and 167.3% in load-bearing capacity and energy absorption capacity, respectively, was attained. SEM imaging revealed that the addition of a few layers at the joint location altered the final failure mode from shear to interlaminar failures without substantially affecting the post-failure behaviour. This study revealed that localised inter-ply hybridisation is an important design parameter for bolted joints so as to enhance the bearing performance of the joint.

Functional Properties of Kenaf Bast Fibre Anhydride Modification Enhancement with Bionanocarbon in Polymer Nanobiocomposites.

The miscibility between hydrophilic biofibre and hydrophobic matrix has been a challenge in developing polymer biocomposite. This study investigated the anhydride modification effect of propionic and succinic anhydrides on Kenaf fibre’s functional properties in vinyl ester bionanocomposites. Bionanocarbon from oil palm shell agricultural wastes enhanced nanofiller properties in the fibre-matrix interface via the resin transfer moulding technique. The succinylated fibre with the addition of the nanofiller in vinyl ester provided great improvement of the tensile, flexural, and impact strengths of 92.47 ± 1.19 MPa, 108.34 ± 1.40 MPa, and 8.94 ± 0.12 kJ m−2, respectively than the propionylated fibre. The physical, morphological, chemical structural, and thermal properties of bionanocomposites containing 3% bionanocarbon loading showed better enhancement properties. This enhancement was associated with the effect of the anhydride modification and the nanofiller’s homogeneity in bionanocarbon-Kenaf fibre-vinyl ester bonding. It appears that Kenaf fibre modified with propionic and succinic anhydrides incorporated with bionanocarbon can be successfully utilised as reinforcing materials in vinyl ester matrix.

Experimental study on silane as an epoxy additive for improving the impact strength of CFRP composites at cryogenic temperatures

The cryogenic fluid storage and transfer have been an area of interest for space applications. Efficient and safe storage of cryogenic fuels like liquid oxygen and liquid hydrogen is very critical. This study focused on the suitability of (3- Aminopropyl)trimethoxysilane as toughening agents for epoxy resin-based systems for cryogenic applications. We focused on diglycidyl ether of bisphenol A (DGEBA) with triethylenetetramine (TETA) as a curing agent at cryogenic temperatures. (3-Aminopropyl) trimethoxysilane was mixed in Epoxy with the help of a magnetic stirrer and ultrasonicator. CFRP panels made of plain weave carbon fiber and silane modified epoxy were fabricated using Vacuum Assisted Resin Transfer Molding (VARTM) technique. Samples were cut out as per ASTM standards, and Izod Impact test was conducted at room and cryogenic conditions. The toughness was witnessed to be improved at both room as well as cryogenic conditions. Silane successfully reduced the indigenous cross linking density of epoxy, which is making it brittle and stronger at the same time. Silane reduces the indigenous cross linking density of epoxy at cryogenic temperatures, which increases its toughness but at the cost of its overall strength. Also the mechanism of fracture and energy dissipation was studied and summarised using macroscopic fracture analysis and FTIR analysis.

Bionanocarbon Functional Material Characterisation and Enhancement Properties in Nonwoven Kenaf Fibre Nanocomposites

Bionanocarbon as a properties enhancement material in fibre reinforced nanobiocomposite was investigated for sustainable material applications. Currently, an extensive study using the micro size of biocarbon as filler or reinforcement materials has been done. However, poor fibre-matrix interface results in poor mechanical, physical, and thermal properties of the composite. Hence in this study, the nanoparticle of biocarbon was synthesised and applied as a functional material and properties enhancement in composite material. The bionanocarbon was prepared from an oil palm shell, an agriculture waste precursor, via a single-step activation technique. The nanocarbon filler loading was varied from 0, 1, 3, and 5% as nanoparticle properties enhancement in nonwoven kenaf fibre reinforcement in vinyl ester composite using resin transfer moulding technique. The functional properties were evaluated using TEM, particle size, zeta potential, and energy dispersion X-ray (EDX) elemental analysis. While the composite properties enhancement was evaluated using physical, mechanical, morphological, thermal, and wettability properties. The result indicated excellent nanofiller enhancement of fibre-matrix bonding that significantly improved the physical, mechanical, and thermal properties of the bionanocomposite. The SEM morphology study confirmed the uniform dispersion of the nanoparticle enhanced the fibre-matrix interaction. In this present work, the functional properties of bionanocarbon from oil palm shells (oil palm industrial waste) was incorporated in nanaobiocomposite, which significantly enhance its properties. The optimum enhancement of the bionanocomposite functional properties was obtained at 3% bionanocarbon loading. The improvement can be attributed to homogeneity and improved interfacial interaction between nanoparticles, kenaf fibre, and matrix.

Electrical characterization of glass fiber reinforced polymer (GFRP) composites for future metasurface antenna applications

In this paper, the Glass Fiber Reinforced Polymer (GFRP) composite samples are explored in order to evaluate their feasibility and adaptability for use in future metasurface antenna application. Multi-layer GFRP composite samples are fabricated with a proportionate ratio of resins and fiber using Vacuum Assisted Resin Transfer Molding (VARTM) technique. N type to waveguide (WR-187) adapter specially designed for electrical characterization of these GFRP composite samples is used. Thru-Reflect-Line (TRL) calibration technique is used for the test setup, and scattering parameters of these GFRP samples is measured by using the manufactured adapter along with the sample holder on a two port Vector Network Analyzer (VNA). Relative permittivity and dielectric loss tangent of GFRP composite samples are computed using Nicholson-Ross-Weir (NRW) and New Non-Iterative conversion methods. The comparative analyses of both methods showed a very good agreement between them. The GFRP sample with the lowest relative permittivity is short listed for its possible application in future metasurface antenna.

The effect of molding process on thermomechanical properties of feather nonwoven reinforced polyester composites

Composites reinforced with feather fibers have attracted the attention of scientists due to their low cost, availability, renewable character and low density. This experimental study emphasizes the effect of molding techniques on the mechanical, thermal and biodegradability properties of feathers nonwoven reinforced polyester composite (FP). The composites were prepared by three methods: resin transfer molding (RTM), infusion and vacuum molding techniques. The morphological analysis revealed excellent compatibility of feather fiber in the matrix. The FP composites made by the three methods showed good insulation performance with thermal conductivity values ranging from 37 mW/(m.K) to 39 mW/(m.K) at 10 °C and the lowest value was observed for the sample developed by the RTM technique. Moisture absorption and the effect of void content on the moisture absorption depend on a number of factors: type of reinforcement, matrix material, molding process and fiber content .The FP composites developed by the vacuum molding technique have shown higher water absorption due to the presence of a high void content. The tensile strength and young's modulus of the FP composites were also examined in this research; the mechanical results showed that the molding techniques clearly affected the performance of the composites. The results obtained in this study have potential applications where high environmental resistance, low cost and durable materials are required.

Tensile and flexural behaviour of glass fibre reinforced plastic – Aluminium hybrid laminate manufactured by vacuum resin transfer moulding technique (VARTM)

The onset of technological advancements has resulted in the need for lightweight materials with superior properties for applications in critical areas such as aerospace and defence sectors, instigating the development of fibre metal laminates (FML). This paper focuses on the evaluation of tensile properties of the 5 layered glass fibre reinforced plastic (GFRP) – aluminium metal sheet (Al) laminate, fabricated by vacuum assisted resin transfer method (VARTM) fitted with spiral tube throughout the periphery of the laminated prepreg. The flexural and tensile properties of the manufactured composite were compared with theoretical values obtained from the FEA simulation of CAD models. The GF- Al composite manufactured by VARTM exhibited excellent properties in agreement with theoretical values that can be apparently attributed to the reduction of void formation in the composite as result of introduction of spirals throughout the length of the glass fibre – aluminium laminated composite.

Integrated vacuum assisted resin infusion and resin transfer molding technique for manufacturing of nano-filled glass fiber reinforced epoxy composite

Vacuum-Assisted Resin Infusion (VARI) and Resin Transfer Molding (RTM) techniques are the most common techniques for the manufacturing of polymeric composite laminates. The VARI technique has a lot of advantages such as low cost, free voids laminates and the ability to produce complex shapes. However, it has some drawbacks such as poor surface finish and temperature instabilities. On the contrary, the RTM technique can withstand high temperature, producing a good surface finish and complex shape laminates. However, it has a high tooling cost and poor quality laminates due to void contents. In this study, a new technique integrated both VARI and RTM techniques is developed to minimize their drawbacks. This technique involves using a semitransparent composite plate instead of a vacuum bag in the VARI technique. This semitransparent plate takes the inverse shape of the composite laminate similar to the RTM tooling. However, this plate has a low cost compared with RTM tooling and allows monitoring of the resin flow during the infusion process. To validate the integrated technique, the mechanical properties of composite laminates are compared with that produced by hand layup technique (HLT). Moreover, the influence of incorporation of 0.25 wt. % and 0.5 wt. % of titanium dioxide (TiO2) nanoparticle into woven and chopped fiber/epoxy composite laminates was demonstrated. The results indicated that the laminates fabricated by the integrated VARI method showed higher mechanical properties than those produced by the hand-layup technique. Moreover, glass fiber/epoxy filled with 0.25 wt. % of TiO2 nanoparticles gives high mechanical properties.

Ultrasonic Welding of Novel Carbon/ Elium® Thermoplastic Composites with Flat and Integrated Energy Directors: Lap Shear Characterisation and Fractographic Investigation.

The current research work presents a first attempt to investigate the welding attributes of Elium® thermoplastic resin and the fusion bonding using ultrafast ultrasonic welding technique. The integrated energy director (ED) polymer-matrix composites (PMCs) panel manufacturing was carried out using the Resin Transfer Moulding (RTM) technique and the scheme is deduced to manufacture a bubble-free panel. Integrated ED configurations and flat specimens with Elium® film of different thickness at the interface were investigated for ultrasonic welding optimization. Optimised weld time for integrated ED and flat Elium® panels with film (0.5 mm thick) configuration was found to be 1 s and 5.5 s, respectively. The ED integrated configuration showed the best welding results with a lap shear strength of 18.68 MPa. The morphological assessment has shown significant plastic deformation of Elium® resin and the shear cusps formation, which enhances the welding strength. This research has the potential to open up an excellent and automated way of joining Elium® composite parts in automotive, wind turbines, sports, and many other industrial applications.

The effect of loading rate on the compression properties of carbon fibre-reinforced epoxy honeycomb structures

The effect of varying strain rate on the compression strength and energy absorption characteristics of a carbon fibre-reinforced plastic honeycomb core has been investigated over a wide range of loading rates. The honeycombs were manufactured by infusing an epoxy resin through a carbon fibre fabric positioned in a dismountable honeycomb mould. The vacuum-assisted resin transfer moulding technique yielded honeycomb cores of a high quality with few defects. Compression tests were undertaken on single and multiple cells and representative volumes removed from the cores in order to assess how the compression strength and specific energy absorption vary with test rate. Crushing tests over the range of strain rates considered highlighted the impressive strength and energy-absorbing response of the honeycomb cores. At quasi-static rates of loading, the compression strength and specific energy absorption characteristics of the unidirectional samples exceeded those of the multidirectional cores. Here, extensive longitudinal splitting and fibre fracture were the predominant failure mechanisms in the cores. For all three stacking sequences, the single-cell samples offer higher compression strength than their five-cell counterparts. In contrast, the specific energy absorption values were found to be slightly higher in the five-cell cores. The experiments highlighted a trend of increased compression strength with loading rate in the multidirectional samples, whereas the strength of the [0°]4 samples was relatively insensitive to strain rate. Finally, the energy absorbing capacity of all structures studied was found to be reasonably constant at increasing rates of strain.

Hygrothermal aging effect on physical and mechanical properties of carbon fiber/epoxy cross-ply composite laminate

Fiber reinforced composites used in aircraft and marine industries lead to critical environmental factors like high temperature and humidity. This work investigates the physical and mechanical response of hygrothermally aged IMA carbon fiber/M21 epoxy CFRP cross-ply composite laminates. The Vacuum assisted resin transfer moulding technique was employed to fabricate two symmetric laminates with a constant fiber volume fraction of 59%. The CFRP laminates with stacking sequence [0, 90, 0, 90]2S and [0, 90]2S were immersed in tap water at 70 °C for more than 6 months up to saturation. The effect of high-temperature submerged environment on the chemical and physical property was determined by the kinetics of moisture absorption rate, FTIR, DSC, and SEM analysis. The mechanical characterization of moisture aged and virgin sample was carried out using tensile test along with post-test failure analysis by SEM micrographs. The moisture absorption followed a typical two-stage model where diffusion rate was increasing proportional to square root of immersion time followed by a sluggish phase up to saturation. The DSC result showed a significant variation in glass transition temperature after aging. SEM micrographs of aged specimen illustrated a matrix dominated failure attributable to fiber-matrix interfacial degradation which finally resulted to a major strength reduction of laminates.

Effect of Lay-up Placement on Physical Properties of Hybrid Composite Reinforced E-glass/Kevlar 49

Hybrid composites have developed and demanding industrial application and replaced metals and non-metal by specific characteristics. The research work concerned with E- glass epoxy and E-glass / Kevlar 49 reinforcement epoxy. The reinforcing materials oriented at 0°/90°, 45°/45° and 30°/60° lay-up placement. The laminate was produced by hand lay-up method Vacuum Bagging Resin Transfer Molding Technique is used for air escape from the mold cavity for effective adhesion between layers of structural composites. The experimental results achieved by conducting hardness of the samples by following the ASTM standard. The ASTM D-2240 durometer was made to perform hardness over the standard samples. The water absorption characteristics of each specimen of different orientation were observed at different humidity level. Electronic weighing balance ASTM D-570 and Electronic densimeter ASTM D-792 was used for water absorption and density respectively. GFK-0°/90° (Glass fiber and Kevlar 0°/90°) has good hardness result and low density, GF 0°/90° has higher density and low water absorption and GFK 30°/60° has higher capability to absorb water than other orientations, Higher density explain the internal structure with low porous structure which has been confirmed due to low water absorption of this material.